Hybrid access system with AGC control of upstream channel transmit power

ABSTRACT

A hybrid access system and method using a hybrid access system point of presence router and a remote link adapter to connect a user computer terminal to a network for fast downstream information transfer by high speed information broadcasting with lower speed upstream information transfer through an independent upstream channel to the hybrid access system point of presence router. High speed downstream information transfer passes through a cable TV headend or a TV transmitter or a cell station.

This is a division of application Ser. No. 08/426,920, filed Apr. 21,1995 now U.S. Pat. No. 5,586,121.

FIELD OF INVENTION

This invention relates to systems and methods for extending a high-speednetwork to remote locations using an asymmetric hybrid access system.

BACKGROUND OF THE INVENTION

Current data communication systems typically use symmetric communicationpaths between transmit and receive sites which have substantially thesame data rates and use the same media in both directions. Such mediamay include coaxial fiber optic or telephone twisted-pair lines. Somenetworks alternatively use broadcast only paths. However no currentnetwork combines the flexibility of full-duplex symmetric networks withthe cost effectiveness of broadcast only networks.

Prior attempts at achieving asymmetric data communications includedmodems with very low speed return channels or systems combining a lowspeed broadcast channel with telephone return lines. However no priorsystems were able to extend a symmetric high-speed backbone network toremote locations at high speeds using an asymmetric hybrid accesssystem. Known prior asymmetric systems are limited to low speed links.

It is desirable to develop a network which combines the flexibility of afull-duplex network with the effectiveness of a broadcast network at areasonable cost.

SUMMARY OF THE INVENTION

According to the present invention a high speed backbone network isextended for communications with remote locations with a hybridasymmetric architecture having fully interactive duplex characteristicsand including independent upstream and downstream communication pathsoperable at separately selectable speeds and protocols. According to oneembodiment of the present invention, the hybrid asymmetric architectureincludes 6 Megahertz television channels downstream and telephone linesfor upstream communications. Alternative downstream communications canbe accomplished according to the invention with a selected highbandwidth broadband service including for example high definitiontelevision (HDTV). Downstream communications according to anotherembodiment can be implemented with a selected low cost, high speedbroadband modem. Downstream communications can provide access to datafrom information sources including companies, government agencies,universities, libraries, and the like. Alternative upstreamcommunications can be accomplished by a narrow band cable TV returnchannel. ISDN, radio, or a selected low-cost, low to medium speedtelephone modem. The asymmetric hybrid system according to the presentinvention includes an interface with the backbone network connected toselected information sources. The interface includes point of presence(POP) circuits implementing high speed downstream communications withlower speed upstream communications. The interface connects the backbonenetwork with cable TV head ends, TV transmitters, cell sites, remoteusers, and upstream and downstream channels.

The present invention further includes a hybrid access configurationwhich uses both downstream and upstream channels. The present inventionfurther includes a hybrid access configuration which uses downstreamwireless TV channels and upstream public switch telephone network(PSTN), wireless RF communications or integrated services digitalnetwork (ISDN) telephone lines. The present invention further includes ahybrid access configuration which uses both downstream and upstreamcable TV channels. The present invention further includes a hybridaccess configuration which has downstream satellite TV channels andupstream public switch telephone network (PSTN), wireless RFcommunications, or integrated services digital network (ISDN) telephonelines.

The present invention further includes packet and acknowledgesuppression methods to eliminate redundant packet, byte, and acknowledgetransmissions in a hybrid access system. A packet is defined as aninformation unit containing one or more bytes of information.Particularly according to the method of the present invention, a certainamount or number of data packets or bytes are enqueued or transmitted ina transmit-ahead window. Transmission of a window of bytes or packets isfollowed by a predetermined time-out period while the transmit queueawaits acknowledgments of packets received. To the extent receiptacknowledgments are received as to particular bytes or packets, thesepackets and bytes in the transmit queue will be deleted from thetransmit queue, and the transmit queue is open to receipt of furtherpackets or bytes for emplacement in slots of the transmission queue forthe deletions made. With respect to acknowledgments placed in atransmission queue, indications acknowledging receipt of later bytes andpackets supersede acknowledgments of earlier transmitted bytes orpackets. Accordingly, under the present invention, the earlieracknowledgments are deleted from an acknowledge transmission queue.

The present invention further includes an automatic address allocationand configuration method in transmissions employing a hybrid accesssystem. According to the present invention, remote users are identifiedinitially with an abstract name, e.g., "Bob," and this abstract name isregistered by the network management system. Configuration isestablished by the downstream routers polling the remote users andregistering the location of the remote user responding to the poll madewith the particular abstract name. Internet Protocol address andupstream channel allocation is accordingly accomplished subject to theconfiguration made including abstract name and identified location.

The present invention further includes a prioritized polling method intransmissions employing a hybrid access system. According to a method ofthe present invention, hybrid upstream routers poll client devices suchas remote link adapters (i.e., "RLAs") according to predeterminedpriority levels. According to one embodiment of the present invention,priority levels are established for state categories of RLAs. Accordingto one embodiment of the present invention, priority level statesinclude status states such as idle. non-responsive, requestingchannel(s), active, or active-credit. According to one embodiment of thepresent invention. RLAs which request a channel are prioritizedaccording to the amount of time its channel requests have goneunfulfilled. According to one embodiment of the present invention hybridupstream routers poll downstream RLAs which are idle more frequentlythan non-responsive RLAs.

The present invention further includes an automatic gain adjustmenttechnique in transmissions employing a hybrid access system, accordingto which a remote link adapter sends successive indications to a hybridupstream router at selected different power levels. When a power levelindication is received by a hybrid upstream router, the receiving hybridupstream router confirms receipt of such indication to the sendingremote link adapter which then registers an associated power level asqualified. According to one embodiment of the present invention, theselected different power levels are dynamically adjusted in magnitude oftransmission level.

The present invention further includes a quality-based upstream channelallocation technique in transmissions employing a hybrid access system.According to the technique, the hybrid upstream router first determinesthe availability of upstream cable channels by a frequency agile RLAsetting a wide range of narrowband upstream channels. The upstreamrouter then makes a quality assessment of available channels in view ofmost recent demand, and it finally selects an upstream channel in viewof the quality assessment made. Quality assessment includesdetermination of busy status and signal characteristics including errorrates, noise floor, and signal to noise ratio. Upstream channels arereleasable according to inactivity or time-out criteria, according towhich release or reassignment occurs responsive to inactivity for over athreshold period. Inactivity is assessed by the hybrid upstream routermonitoring operability indications and data packets received fromassigned RLAs.

The present invention further includes a credit allocation technique intransmissions employing a hybrid access system. According to a method ofthe present invention, an upstream channel is shared by a plurality ofRLAs in accordance with a credit criterion, and credit control packetsare dispatched to a RLA which permit the RLA to send data packets toarbitrary hosts. Upon sending a data packet, the RLA returns the creditcontrol packet to a server containing software including Hybridware™code which manages data flows. The Hybridware™ code or Hybridware™server, according to one embodiment of the present invention, includessoftware distributed among data processors in the upstream anddownstream routers and elsewhere in the HASPOP, including for example inthe network management system.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a detailed schematic drawing of a hybrid access systemconnected to a backbone network such as the Internet, and having pointsof presence connecting the backbone network to cable TV headends, TVtransmitters, or Logical Nodes (e.g., cell sites), with remote usersconnecting to an RLA which in turn connects to downstream TV channelsand independent lower speed upstream channels:

FIG. 2a is a schematic drawing of a hybrid access system point ofpresence (POP) according to the present invention including at least asingle host computer or server and at least a single router including ahybrid downstream router, a hybrid upstream router, a dial-up router, anInternet router, or a backbone network router, and a POP LAN switch:

FIG. 2b is a block diagram of a downstream router according to thepresent invention;

FIG. 2c is a block diagram of an upstream router according to thepresent invention;

FIGS. 3a, 3b, and 3c comprise a pictorial diagram of a hybrid accesssystem according to the present invention according to which a remoteuser can communicate with an information provider through the hybridaccess system;

FIG. 4 is a logical data flow diagram showing data flows between aserver and a client computer of the hybrid access system according tothe present invention;

FIG. 5 is a flow chart of operation of a two-way cable networkembodiment of the hybrid access system according to the presentinvention:

FIG. 6 is a flow chart of operation of a one-way cable networkembodiment of the hybrid access system according to the presentinvention, including provision for upstream telephone system data flow;

FIG. 7 is a Hybridware™ server state diagram of the upstream channelallocation method according to the present invention;

FIG. 8 is a Hybridware™ client state diagram of the upstream channelallocation method according to the present invention;

FIG. 9 is a logical data flow diagram showing data flows between routerserver and client computers of the hybrid access system for automatichandling of multiple clients according to automatic address allocationmethods of the present invention;

FIG. 10 is a flow chart of address allocation control protocol accordingto the present invention;

FIG. 11 is a state diagram of the hybrid adaptive gain control protocolaccording to the present invention;

FIG. 12a is a transmission diagram of information exchange between twonodes in an asymmetric network according to the present invention,having a high downstream data rate of n bits per second and a lowerupstream data rate of m bits per second;

FIG. 12b is a diagram of conventional downstream messaging of firstthrough fourth data packets, 100, 250, 325, and 450, between first andsecond nodes, in parallel with upstream transmission of receiptacknowledge indications;

FIG. 12c is a diagram of a conventional transmission buffer queue in aRLA of a remote client station;

FIG. 12d is a diagram indicating a redundant acknowledgment packet in aconventional transmission buffer queue in a RLA of a remote clientstation;

FIG. 12e is a diagram of a conventional transmission buffer queue,indicating no need for an earlier acknowledgment (ack 100) packet inview of a new acknowledgment (ack 210) packet that supersedes theearlier acknowledgment packet;

FIG. 12f is a diagram of first through fourth network nodes seriallyconnected to each other in accordance with the present invention,wherein the link between the second and third nodes is asymmetric andthat between the first and second and the third and fourth nodes aresymmetric;

FIG. 13 is a tabular description of transmission controlprotocol/Internet protocol (TCP/IP) data transmission packet protocolheader as used in connection with the present invention;

FIG. 14a is a diagram of a sequential data transmission between firstand second network nodes, according to the present invention;

FIG. 14b is a diagram of the contents of a conventional transmissionqueue in the downstream node during a first time period;

FIG. 14c shows the contents of a transmission queue in a downstream nodeduring a later time period, eliminating retransmission of the 300packet, according to the present invention, because another 300 packetwas already in the transmission queue;

FIG. 15 is a flow diagram of the acknowledge suppression methodaccording to the present invention;

FIG. 16 is a flow diagram of the packet suppression method according tothe present invention;

FIG. 17 is a flow diagram of information exchanges between Hybridware™server and client, under conditions in which the client has noinformation to transmit;

FIG. 18 is a flow diagram of information exchanges between Hybridware™server and client, under conditions in which the client has informationto transmit and the server gradually allocates bandwidth to the client;

FIG. 19 is a flow diagram of information exchanges between Hybridware™server and client, under conditions in which the server allocates theclient a dedicated channel, the client transmits data and periodicallyreports to the server with done messages; and

FIG. 20 is a flow diagram of information exchanges between Hybridware™server and client, under conditions in which a dedicated channel isconverted into a shared channel.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a detailed schematic drawing of a hybrid access system 1according to the present invention, showing a RLA and user workstation29 connected through hybrid access system 1 to a variety of entitiesconnected to a backbone network 20 such as Internet, includinginformation providers 21, corporations 22, government agencies 23,universities 24, and others 25. A backbone network is one which istypically not directly connected to a user. Hybrid access system 1according to an embodiment of the present invention includes hybridaccess system (HAS) points of presence (POPs) 26 and other points ofpresence 27. HASPOPs 26 include individual HASPOPs 26 (1)-26(3) whichenable communication over a broadband network, either by upstream anddownstream cable communications or by downstream cable and upstreamtelephone communications or various other hybrid configurations (e.g.,wireless or satellite). The present invention particularly includes (1)a hybrid access configuration which uses downstream cable TV channelsand upstream public switch telephone network (PSTN), wireless RFcommunications or integrated services digital network (ISDN) telephonelines; (2) a hybrid access configuration which uses downstream wirelessTV channels and upstream public switch telephone network (PSTN),wireless RF communications or integrated services digital network (ISDN)telephone lines, (3) a hybrid access configuration which uses bothdownstream and upstream cable TV channels; (4) a hybrid accessconfiguration which uses both downstream and upstream wireless channels;and (5) a hybrid access configuration with downstream satellite channelsand upstream PSTN, wireless RF communications or ISDN telephonechannels.

Backbone network 20 such as the Internet which includes a plurality ofInternet servers 20' connected to HASPOPs 26 each including a pluralityof host computers and/or servers, collectively referred to as hybridservers. Hybrid access system 1 further includes broadcast units suchas, a cable television (TV) head end 28, independent upstream channels28: and a RLA 29, U.S. Pat. No. 5,347,304 (1994) assigned to HybridNetworks, Inc., and describing an example of an RLA is hereby expresslyreferenced and incorporated herein in its entirety. An RLA may receiveanalog broadcast signals including encoded digital information which theRLA decodes and provides to a data terminal or computer. According to anembodiment of the present invention, the downstream flow of informationproceeds from HASPOPs 26(1)-26(3) through cable TV head end or TVtransmitters 28 or cell sites 30 and through RLA and user workstation29. Upstream information flow proceeds in one case from RLA and userworkstation 29 through independent upstream channels 28; to HASPOP26(1), and then to backbone network 20; alone T1 or T3 or other digitallines. In another case, upstream information proceeds from userworkstation through RLA 29 through the cable TV network, and cable TVhead end 28 to hybrid access system point of presence and then throughT1, T3, or other digital lines to backbone network 20; The outputs ofthe cable TV headends or TV transmitters 28 include pluralities of highspeed downstream broadband radio frequency, i.e., RF, channels connectedto respective remote users 29. Hybrid access system 1 further includes aplurality of cell sites 30 connected through high speed links to acorresponding hybrid access system point of presence 5. The outputs ofcell sites 30 include pluralities of high speed downstream broadbandchannels connected to selected remote users 29. A particular remote user29 can be connected via an independent lower speed upstream channel to ahybrid access system point of presence 26 as discussed below or via asimilar independent lower speed upstream channel to another point ofpresence system 27. By lower speed it is meant at a speed reduced fromthe speed of the high speed link used to transmit informationdownstream. A particular hybrid access system point of presence 5 can beconnected via duplex high speed links to a plurality of cable TVheadends or TV transmitters, to a plurality of cell sites 30, or acombination of cable TV headends or TV transmitters 28 and cell sites30.

FIG. 2a is a schematic drawing of a point of presence (POP) system 26(1)according to the present invention, including host computers or servers39 and a POP local area network, i.e., LAN switch 33 to which hostcomputers or servers 39 are connected. Further connected to LAN switch33 are one or more downstream and one or more upstream hybrid accessSystem point of presence routers, respectively 34 and 35, one or moredial-up routers 36, a network management system 37, and conventionalrouters 38. Connected to POP LAN switch 33 are one or more data storageelements or systems. Each downstream hybrid access system point ofpresence router 34 is connected with a high speed link to a TVtransmitter or cable TV headend, for example. Further, each upstreamhybrid access system point of presence router 35 is connected to aplurality of independent upstream channels, which operate at a lowerspeed than the downstream high speed links to TV transmitters or cableTV headends. Each dial-up router 36 is connected to a plurality ofindependent upstream channels operating at a lower speed than theindicated downstream high speed links. Each conventional router 38 isconnected along a high speed line to wide area network (WAN) lines toselected information providers, Internet, or other nodes or businesses.POP LAN switch 33, according to one embodiment of the present inventionis connected directly along a high speed line to wide area network (WAN)lines to selected information providers, Internet, or ocher nodes orbusinesses.

FIG. 2b is a block diagram of hybrid downstream router 34 according tothe present invention. In particular, downstream router 34 includesnetwork interface 34a, link interface 34b, physical interface 34c,controller 34d, physical interface 34e, link interface 34f, and networkinterface 34g. Downstream router 34 and physical interface 34e areconnected to POP LAN switch 33 for sending and receiving information,and physical interface 34e, link interface 34f, and network interface34g are serially connected to each other and to controller 34d forbidirectional communication of selected information. Additionally,controller 34d is connected directly to each of physical interface 34eand link interface 34f along indicated lines to accomplish control andmessaging functions. Downstream router 34 and physical interface 34c areconnected to cable TV headends, TV broadcast sites, cell cites or thelike, to communicate information primarily or exclusively in aunidirectional or downstream direction, and physical interface 34c, linkinterface 34b, and network interface 34a are serially connected to eachother and to controller 34d for selected communication of selectedinformation. Additionally, controller 34d is connected directly to eachof physical interface 34c and link interface 34b along indicated linesto accomplish control and messaging functions. Downstream router 34 mayinclude one or more of physical interfaces 34c. According to anembodiment of the present invention, router 34 may be a bridge withoutnetwork interfaces 34a and 34g or a connection without networkinterfaces 34a and 34g and without link interfaces 34b and 34f.According to yet another embodiment of the present invention, router 34can be a gateway.

FIG. 2c is a block diagram of upstream router 35 according to thepresent invention. In particular, upstream router 35 includes networkinterface 35a, link interface 35b, physical interface 35c, controller35d, physical interface 35e, link interface 35f, and network interface35g. Upstream router 35 and physical interface 35e are connected to POPLAN switch 33 for sending and receiving information, and physicalinterface 35e, link interface 35f, and network interface 35g areserially connected to each other and to controller 35d for bidirectionalcommunication of selected information. Additionally controller 35d isconnected directly to each of physical interface 35e and link interface35f along indicated lines to accomplish control and messaging functions.Upstream router 35 and physical interface 35c are connected to upstreamchannels, e.g., telephone links for example, to communicate informationprimarily or exclusively in a unidirectional or upstream direction, andphysical interface 35c, link interface 35b, and network interface 35aare serially connected to each other and to controller 35d for selectedcommunication of selected information. Additionally, controller 35d isconnected directly to each of physical interface 35c and link interface35b along indicated lines to accomplish control and messaging functions.Upstream router 35 may include one or more of physical interfaces 35c.According to an embodiment of the present invention, router 35 may be abridge without network interfaces 35a and 35g or a connection withoutnetwork interfaces 35a and 35g and without link interfaces 35b and 35f.According to vet another embodiment of the present invention, router 35can be a gateway.

FIG. 3a-3b are drawings of a hybrid access system 1 according to thepresent invention according to which remote user having a workstation 2or connected to LAN 61, as shown respectively in FIGS. 3b and 3c cancommunicate with a selected information provider 21 including LAN 50,bridge or router 51 connected to LAN 50, and dial-up router 52 connectedto LAN 50 through a hybrid access system point of presence 26. Further,HAS POP is connected along a high speed link to bridge or router 51.Additionally, HAS POP 26 is linked to other information providers toreceive selected information items. Additionally, dial-up router 52 isconnected to a plurality of upstream channels. FIGS. 3b and 3cadditionally show respective first and second users, in one caseincluding workstation 2 in turn including a RLA 60 and in the otherinstance including RLA 60 and a local area network (LAN) 61 connected toRLA 60. First user 29(1) is connected to an upstream channel from userworkstation 2, and second user 29(2) is connected to an upstream channeldirectly from RLA 60. In the case of each user, RLA 60 receives inputinformation, particularly radio frequency (RF) information along one ofrespective input channels connected thereto.

FIG. 4 is a logical data flow diagram showing data flows between aserver and a client computer of the hybrid access system 1 according tothe present invention. Hybrid access system 1 includes a serverapplication 70, a hybrid system manager 71, and a Hybridware™ server 72connected to LAN 38. Hybrid access system 1 further includes aHybridware™ client 73 and a client application 74 operating withHybridware™ client 73. Hybridware™ client 73 communicates withHybridware™ server 72, as transmitter alone upstream channel 75 or asreceiver along downstream channel 76. Downstream data traffic isexpected to be higher capacity than upstream data traffic: Hence, thebolder depiction of downstream channel 76 than upstream channel 75.

FIG. 5 is a flow chart of operation of a two-way cable networkembodiment of hybrid access system 1 according to a hybrid protocolembodiment of the present invention. In particular, according to oneembodiment of the hybrid protocol of the present invention, clientapplication 74 sends 100 data to server application 70 in an upstreamdirection, thereby issuing a connection request. Hybridware™ client 73buffers the data received and checks if it controls an upstream datachannel. If it does, then the data is transmitted forthwith. If itdoesn't, Hybridware™ client 73 queues up the data message and creates101 a channel request for a particular subchannel within upstreamchannel 75. Hybridware™ client 73 then waits 102 for a poll fromHybridware™ server 72, i.e., Hybridware™ router. According to anembodiment of the present invention, prioritized polling is conductedwhereby not all clients are polled at the same frequency. Clients in anidle state are polled relatively frequently. Clients in blocked andNON-RESP states are polled but not at the same relatively highfrequency. Clients in an ACTIVE state are not polled at all. This isbased on the assumption that an active client has what it wants and thatit is most important to respond quickly to new connections coming fromclients in an IDLE state. Those clients coming from a NON₋₋ RESP cyclereceive second order attention and can wait a little longer, since theymay have already been in a state where communication are impossible andmay have been in that state for a considerable period of time. Accordingto one embodiment of the present invention, a poll cycle is the smallestperiod such that all but active clients are polled at least once. Idleclients may be polled multiple times during one poll cycle. Blocked andnon₋₋ resp clients are distributed evenly across the poll cycle toassure that the latency for acquiring a channel for idle units isuniform. All clients are grouped according to their state and polledwithin each group according to the round robin approach according whicheach of a series is polled in sequence and then the same sequence isrepeatedly polled individual by individual. Upon receipt of a poll,Hybridware™ client 73 sends 103 a channel request via lower speedupstream channel 75. Hybridware™ router 72, i.e., server, receives 104the channel request from Hybridware™ client 73 and initially sends 105 alogin message to Hybridware™ system manager 71. Hybridware™ systemmanager 71 verifies 106 that Hybridware™ client 73 is an authorized userof data processing services on the particular node or system withinwhich hybrid access system 1 operates. Then, Hybridware™ router 72receives 107 a login response message from Hybridware™ system manager 71through LAN 38, which indicates whether the client is allowed to operateon the particular network and which contains other operatingcharacteristics of Hybridware™ client 73. Hybridware™ router 72 thenallocates 108 (see state diagrams of FIGS. 7 and 8) an upstream channel75 for Hybridware™ client 73, depending on channel availability andsuitability. Suitability depends on factors including but not limited tochannel quality, type of service required, operating characteristics ofHybridware™ client 73, configuration restrictions, and the like.Hybridware™ router 72 sends 109 an upstream channel allocation messageto Hybridware™ client 73 via high speed downstream channel 76, which mayaccording to one embodiment of the present invention specify thefrequency on which Hybridware™ client 73 is permitted to transmit.Thereafter, Hybridware™ client 73 receives 110 an upstream channelallocation. Next, Hybridware™ client 73 tunes 111 to the specificallyallocated upstream data channel frequency on which it is permitted totransmit data. Finally, Hybridware™ client 73 sends 112 the selectedapplication data from client application 74. Accordingly, clientapplication 74 and server application 70 are able to send and receive113 data via upstream bandwidth management of an asymmetric hybridaccess system, according to the present invention.

FIG. 6 is a flow chart of operation of a one-way cable networkembodiment of the hybrid access system 1 according to the presentinvention, including provision for upstream telephone system data flow.According to this embodiment of the present invention, when clientapplication 74 needs to communicate with server application 70 in anupstream direction. Hybridware™ client 73 dials 202 Hybridware™ router72. Then, Hybridware™ client 73 sends 203 a channel request via lowerspeed PSTN upstream channel (not shown). Hybridware™ router 72 receives204 the channel request and sends 205 a login message to Hybridware™system manager 71. Hybridware™ system manager 71 verifies 206Hybridware™ client 73 as an authorized user. Then, Hybridware™ router 72receives 207 a login response from Hybridware™ system manager 71.Hybridware™ router 72 sends 208 an authorization message to Hybridware™client 73 via high speed downstream channel 76. Hybridware™ client 73receives 209 the authorization message for use of a selected upstreamPSTN channel. Finally, Hybridware™ client 73 sends 212 the selectedapplication data. Accordingly, client application 74 and serverapplication 70 are able to send and receive 213 selected data via theasymmetric hybrid access system 1.

FIG. 7 is a Hybridware™ server state diagram for upstream channelallocation of the hybrid access system according to one embodiment ofthe present invention. According to the state diagram of FIG. 7, theHybridware™ server can be in one of four states: IDLE 301, NON₋₋ RESP304, BLOCKED 302, or ACTIVE 303. In the IDLE state, the Hybridware™server expects an IDLE poll response. If there is no request to theclient from the application or a channel request message, or if there isapplication data that needs to be sent in the upstream direction. Uponreceiving a channel request message, the server transitions the clientto a BLOCKED state. In a BLOCKED state, the server sends one of twomessages to the client, a channel allocation message or a no channelavailable message. Upon sending a channel allocation message, the servertransitions the client to an ACTIVE state. Upon sending a no channelavailable message, the client remains in a BLOCKED state. The clientwill remain in the BLOCKED state until either a channel becomesavailable in which case the server will transition the client to theACTIVE state or the server receives a channel release message in whichcase the server will transition the client to the IDLE state. In theACTIVE state, the server does not poll the client. The servertransitions the client from ACTIVE to IDLE upon receiving a channeldeallocation message or upon detecting a system defined inactivitytime-out. In the ACTIVE state, the server waits for a periodic heartbeatmessage from the client. The Hybridware™ server software awaits periodicheartbeat messages from the client at selected time intervals. Theserver software monitors other channel quality parameters includingerrors and signal to noise ratios. If the server stops hearing a certainnumber of operability indications or signals within a system definedinterval as to a particular client, or if particular parameters (e.g.,signal to noise ratio) exceed a predetermined threshold, then the serversends a directed poll to the particular client. Essentially, the clientis instructed to respond on another control frequency. If the clientresponds on the designated control frequency, the server reassigns theupstream channel to the client, so that it can continue to operate. Ifnot, the client is deemed NON₋₋ RESP. Channel quality monitoring andchannel reassignments are done transparently to the user and theapplications. If a certain, system defined, consecutive count ofheartbeat messages is missed, the server issues a special poll messageor directed poll. If the client does not respond, the server transitionsto the NON₋₋ RESP state. If the client responds to the poll, the servereither remains in the ACTIVE state or transitions to the IDLE state. Theformer happens, if the client responds with a channel request message,and the latter happens, if the client responds with an IDLE pollresponse. In the former case, the server may decide to assign adifferent upstream channel to the client. In the BLOCKED or IDLE state,the server will transition the client to NON₋₋ RESP, i.e.,"non-responsive," state after the client fails to respond to a systemdefined number of polls. The NON₋₋ RESP state is almost identical interms of state transition to idle state, a difference being that an IDLEpoll response transitions the client into an IDLE state.

FIG. 8 is a Hybridware™ client state diagram for upstream channelallocation of the hybrid access system 1 according to an embodiment ofthe present invention, involving two way cable communication. Accordingto this embodiment, the hybrid upstream client protocol has threestates. IDLE 401, CON₋₋ REQ, i.e., "connect request" 402, and ACTIVE404. In the IDLE state, the client, when polled, will transmit an IDLEpoll response, if there is no request from the application. However, itwill respond with a channel request message, if there is data that needsto be sent upstream. Upon transmitting a channel request message, theclient transitions to a CON₋₋ REQ state. In the CON₋₋ REQ state, theclient expects one of two messages from the hybrid router, a channelallocation or a no-channel allocation signal. Upon receiving a channelallocation message, the client informs the application and tunes to thechannel it was allocated and transitions to the ACTIVE state. Uponreceiving a no-channel available message, the client informs theapplication and transitions to the IDLE state. In the ACTIVE state, theclient forwards data messages application to the upstream transmitter.In the ACTIVE state, the client further monitors the applicationactivity and if it detects that no data has moved from the applicationto the upstream transmitter for a system defined period of time, it willsend a channel deallocation request and transition to an idle state. Inan ACTIVE state, the application may explicitly request that the channelbe released, in which case the client will send a channel deallocationrequest to the hybrid router and will transition to the IDLE state. Inthe ACTIVE state, the client periodically sends an operabilityindication message to the server. If the client receives a poll messageduring the ACTIVE state, it will send a channel request message and willtransition to a CON₋₋ REQ state. The hybrid router may also send anunsolicited channel release message, in which case the client willnotify the application and transition from ACTIVE state to IDLE state.

FIG. 9 is a logical data flow diagram showing data flows between serverand client computers of the hybrid access system 1 according to thepresent invention, for multiple clients under an address allocationprotocol simplifying distribution of ip addresses to remote systems. Theprotocol according to the present invention determines where a givenHybridware™ client is located and how to download its ip address, giventhat the client has no address yet. Hybrid access system 1 includes aserver application 70, a hybrid system manager 71, and Hybridware™servers 72a & 72b connected to LAN 38. Hybrid access system 1 furtherincludes Hybridware™ clients 73a and 73b and client applications 74a and74b operating with respective ones of Hybridware™ clients 73a and 73b.Hybridware™ client 73a communicates with Hybridware™ server 72a, astransmitter along upstream channel 75a or as receiver along downstreamchannel 76a. Hybridware™ client 73b communicates with Hybridware™ server72b, as transmitter along upstream channel 75b or as receiver alonedownstream channel 76b. Downstream data traffic is expected to be highercapacity than upstream data traffic: Hence, the bolder depiction ofdownstream channels 76a and 76b than upstream channels 75a and 75b.

FIG. 10 is a flow chart of address allocation control according to anembodiment of the present invention to logon and configure Hybridware™clients with a selected unique node name which is entered in theconfiguration database in the hybrid system manager 71 which is thesoftware portion of network management system 37. In particular, hybridsystem manager 71 sends a new client message to all hybrid routers 72aand 72b after learning of particular new clients by message, mail, ortelephone call (step 500 in FIG. 10). At this point the hybrid systemmanager is aware of a Hybridware™ client identification name andequipment serial number, but has not associated the clientidentification name with a separate unique client address (e.g.,Internet Protocol, or IP address) provided by separate automaticregistration. Each hybrid router 72a and 72b periodically broadcasts aconfiguration poll message (step 501). Hybridware™ clients recognizetheir preselected unique names during a configuration poll (step 502).Hybridware™ clients 72a and 72b respond to the configuration poll.Hybrid routers 72a and 72b receive respective configuration pollresponses. Then, hybrid routers 72a and 72b send respective client foundmessages to system manager 71. System manager 71 then sends a ceaseconfiguration poll message to all hybrid routers. Further, systemmanager 71 allocates an Internet protocol (IP) address and otherconfiguration data for each new client according to the preselectedunique names. System manager 71 sends the IP address and otherconfiguration data to the applicable hybrid router 72a, 72b. Then, theapplicable hybrid router 72a, 72b sends, using broadcast or unicast andthe unique name, the corresponding IP address and other configurationdata to the applicable Hybridware™ client. As a result, the Hybridware™client receives the IP address and other configuration data determinedand reconfigures appropriately. In summary, according to the presentinvention, an automatic address allocation and configuration method intransmissions employs a hybrid access system. Remote users areidentified initially with a unique abstract name, e.g., "Bob," and thisabstract name is registered by the network management system.Configuration is established by the upstream routers polling the remoteusers and registering the location of the remote user responding to thepoll made with the particular abstract name. Upstream channel allocationis accordingly made subject to the configuration made including abstractname and identified location. Automatic address allocation andconfiguration is accordingly accomplished on line at an initial log-onsession with a new user. The method of the present invention isaccordingly swift and simple, eliminating registration delaysexperienced by many known log-in systems.

FIG. 11 is a state diagram of the hybrid adaptive gain control protocolaccording to the present invention, which overcomes noise andattenuation while transmitting on cable in an upstream direction. Thehybrid adaptive gain control protocol has a SEARCHING state 600 and aSTABLE state 601. In the STABLE state 601, the protocol evaluates pollmessages from the hybrid router. If a poll message indicates loss of apoll response, the protocol transitions to the SEARCHING state 600. Pollresponses are transmitted at a fixed power level. In the SEARCHING state600, the client system responds to polls with a poll response at largerand larger power levels. After receiving a system specified, number ofconsecutive polls with an indication of a successful poll response, thesystem transitions to a STABLE state.

FIG. 12a is a transmission diagram of information exchange between nodesA and B. Nodes A and B comprise an asymmetric network according to thepresent invention, having a high downstream data rate of n bits persecond and a lower upstream data rate of m bits per second. Thedownstream data rate n is greater than the upstream data rate m. Node Bincludes receive and transmission queues to hold information receivedand to be sent, including acknowledge indications or messages. Theacknowledge suppression method according to the present inventionrelates to the node or system transmitting data acknowledgments, whichacknowledges receipt of either data packets or data bytes contained inincoming packets. The numbers on data packets indicate the position ofthe last data byte of the packet in the data stream, and theacknowledgment numbers indicate that all the bytes of the data stream upto and including the byte indicated have been received. According to themethod of the present invention, the acknowledgment of byte k (or packetnumber k) indicates that all bytes or packets prior to k have beenreceived. According to a method of the present invention, the transmitqueue queues up additional acknowledgment packets as new packets arereceived. FIG. 12b is a diagram of messaging of first through fourthdata packets, 100, 250, 325, and 450, between upstream and downstreamnodes, in parallel with upstream transmission of receipt acknowledgeindications with respect to only two data packets, namely 250 and 450.FIG. 12c is a diagram indicating acknowledgment of first and secondpacket receptions during a first time period. In particular, packet 1(i.e., "pkt 1") is currently being sent, and an acknowledge (i.e., "ack250") message is currently being appended at the end of the transmitqueue. FIG. 12d is a diagram indicating acknowledgment of another packetduring another period. FIG. 12e is a diagram indicating no need for anacknowledge 100 signal in view of a subsequent acknowledgment havingbeen successful. In particular, according to the acknowledge suppressionmethod of the present invention, not all acknowledgment packets will besent to node A, because the "ack 210" message carries information whichsupersedes the "ack 100" message. Accordingly, the amount of traffic onthe communication link from B to A is reduced, according to the presentinvention. In general, this introduces an acknowledge latency, but whereall messages queued up for transmission are acknowledgments,acknowledgment latency is reduced. For example, when an "ack 15" signalis transmitted and an "ack 100" message awaits transmission, and an "ack210" message is appended to the queue, the acknowledge suppressionmethod according to the present invention will delete the "ack 100"message as superfluous. Any new acknowledgments appended while "ack 15"is being transmitted will result in deletions of unnecessaryacknowledgments keeping queue length to two. Upon transmit completion of"ack 15," the next acknowledgment, e.g., "ack 210" will be transmitted.Accordingly, the method of the present invention eliminates unnecessarytransmission of "ack 100" signals and provides for reducedacknowledgment latency for "ack 210." The ack suppression methodaccording to the present invention, accordingly reduces the probabilityof queue overflow and potential out of memory conditions in system B. Itreduces the load on the communication link from B to A, and in somecircumstances reduces acknowledgment latency for data transfers from Bto A. FIG. 11f is a diagram of first through fourth network nodesserially connected to each other in accordance with the presentinvention, wherein the link between the first and second nodes issymmetric, the link between the second and third nodes is asymmetric andthat between the third and fourth nodes is symmetric. The acknowledgesuppression method of the present invention applies to both thecommunications system of FIG. 12a, in which nodes A and B are end nodes,as well as to the communications system of FIG. 12f, in which nodes Band C are intermediate systems such as a router, and data packetsoriginating at node D are transmitted through router nodes C and B to acentral system connected to node A.

FIG. 13 is a tabular description of a transmission controlprotocol/Internet protocol (TCP/IP) data transmission packet protocolheader as used in connection with the present invention. The first five32 bit words and the following IP options are referred to as the IPheader. The five words following the IP options together with the wordscontaining TCP options are referred to as the TCP header. The non-ackTCP header is the TCP header less the acknowledgment number field.

FIG. 14a shows sequential data transmission between first and secondnodes, according to the present invention. As shown in FIG. 14a, datapackets or bytes 100-700 are transmitted from node A to node B.Concomitantly, acknowledge messages, "ack 100," "ack 200," and "ack 300"were dispatched from node B to node A.

FIG. 14b shows a data packet sequence of packets 100-400 held in thetransmit queue during a first time period, followed by a singleacknowledgment, "ack 100."

FIG. 14c is a diagram of a data packet sequence transmitted during alater time period, eliminating retransmission of the 300 packet, becauseanother 300 packet was already in the transmission buffer,

FIG. 15 is a flow diagram of an acknowledge suppression (AS) method,i.e., an AS method, according to the present invention in which receiptof information transmitted from system A to system B over a firstindependent simplex communication link is acknowledged by system B. Themethod of the present invention starts 1500 at a particular time, and afirst packet Mi of information is received 1501. If the transmit queueis not empty 1502, the header of the last packet Mi+1 on the transmitqueue is obtained 1503. If the transmit queue is empty 150, then Mi isenqueued 1509 and the AS method according to the present invention iscompleted. If the header of the next packet Mi+1 on the transmit queueequals 1504 the header of packet Mi, and the NON-ACK TCP header of Miequals 1505 the NON-ACK TCP header of Mi, then Mi+1 is discarded 1506.If the header of the last packet Mi+1 on the transmit queue does notequal 1504 the header of packet Mi, or the NON-ACK TCP header of Mi doesnot equal 1505 the NON-ACK TCP header of Mi, then Mi is enqueued 1509and the AS method according to the present invention is completed. IfMi+1 is not the last message on the queue 1507, then the header on thenext packet Mi+1 on the transmit queue is obtained 1508, and acomparison is done to determine whether the header of the last packetMi+1 on the transmit queue equals 1504 the header of packet Mi. If Mi+1is the last message on the queue 1507, then Mi is enqueued 1509 and theAS method according to the present invention is completed.

FIG. 16 is a flow diagram of the packet suppression (PS) methodaccording to the present invention. The method of the present inventionstarts 1600 at a particular time, and a first packet Mi of informationis received 1601. If the transmit queue is not empty 1602, the header ofthe last packet Mi+1 on the transmit queue is obtained 1603. If thetransmit queue is empty 1602, then Mi is enqueued 1609 and the PS methodaccording to the present invention is completed. If the header of thelast packet Mi+1 on the transmit queue equals 1604 the header of packetMi, then Mi+1 is discarded 1606. If the header of the last packet Mi+1on the transmit queue does not equal 1604 the header of packet Mi, thenMi is enqueued 1609 and the PS method according to the present inventionis completed. If Mi+1 is not the last message on the queue 1607, thenthe header on the next packet Mi+1 on the transmit queue is obtained1608, and a comparison is done to determine whether the header of thelast packet Mi+1 on the transmit queue equals 1604 the header of packetMi. If Mi+1 is the last message on the queue 1607, then Mi is enqueued1609 and the PS method according to the present invention is completed.

FIG. 17 is a flow diagram of information exchanges between Hybridware™server and client, according to conditions in which the client has nodata to transit. A credit (1,F) corresponding to a single predeterminedamount of data, e.g., ten bytes, or ten packets at a selected frequencyF, is transmitted from node A to node B, and a done signal DONE(0,0) istransmitted from node B to node A, indicating that no data packet wastransmitted, leaving the existing credit level of the particular channelunchanged. The credit protocol according to the present inventionpermits single upstream cable channels to be shared by multiple remotelink adapters. Alternatively, single upstream channel is controlled andused by a single remote link adapter until the channel is relinquished.The present invention includes an allocation method in transmissionsemploying a hybrid access system. According to a method of the presentinvention, an upstream channel is shared by a plurality of remote linkadapters in accordance with a credit criterion, and credit controlpackets are dispatched to a remote link adapter which permit the remotelink adapter to send data packets to arbitrary hosts. Upon sending adata packet, the remote link adapter returns the credit control packetto a Hybridware™ server. A credit permits a remote link adapter to senda certain number of packets up to a maximum number controlled by aconfiguration parameter MAX₋₋ CREDIT₋₋ PACKETS, thereby eliminatingpolling for that period. If a remote link adapter does not have a datapacket to send, it returns the credit to the hybrid access systemwithout sending any data packets. The remote link adapter then sets afield in the credit control packet to the number of packets which wassent. If the protocol process at the server does not receive creditstatus information from the credit control packet within a certaincredit time-out, CREDIT₋₋ TIMEOUT, in milliseconds, for a certain numberof times, FAIL₋₋ CNT, consecutively, the remote link adapter is assumedto be in error and is put in a not-responding state (NON-RESP). Theoverall upstream channel performance of a remote link adapter using acredit channel is lower than a remote link adapter on a sole useupstream channel. If any sole use upstream channel becomes available,this channel is given to the credit remote link adapter that has beenwaiting the longest for a sole use upstream channel that currently haspackets to send.

FIG. 18 is a flow diagram of information exchanges between Hybridware™server and client, according to conditions in which the client hasinformation to transmit and the server gradually allocates bandwidth tothe client. In particular a node first provides a single credit at aselected frequency F. Then a packet is sent, consuming the credit,followed by a completion message indicating use of one credit andpotential for an additional transmission corresponding to three credits.Next, a credit is provided corresponding to two packets at the selectedfrequency F, which is followed by two packet transmissions and acompletion message indicating consumption of two credits and potentialfor transmission of one more. In response, another double credit is sentfollowed by a single packet and an acknowledgment of transmission of oneand potential for no more transmissions.

FIG. 19 is a flow-diagram of information exchanges between Hybridware™server and client, according to conditions in which the server allocatesthe client a dedicated channel, the client transmits data andperiodically reports to the server with done messages. In particular, acredit indication dedicating a channel at frequency F is provided,followed by 235 packet transmissions. According to prearrangement, aoperability indication in the form of a DONE message is provided at anestablished time indicating potential for five more packettransmissions. The done message indicates completion of 235 packettransmissions as an accounting function. Because the channel isdedicated, further packet transmissions are made without specificfurther credit allocations.

FIG. 20 is a flow diagram of information exchanges between Hybridware™server and client, according to conditions in which a dedicated channelis converted into a shared channel. In particular, a credit indicationcode D indicating a dedicated channel at frequency F is provided,followed by transmission of 235 packets and a credit message stoppingchannel dedication and switching to a credit mode. Responsive to thecredit message a DONE signal accounts for the 235 packets transmittedduring the dedicated mode and indicates potential for five moretransmissions. This is followed by a credit allocation or one at aselected frequency. Thus, one packet is transmitted, followed by acompletion indication specifying potential for four more packets to betransmitted.

What is claimed is:
 1. In a two way asymmetric network communicationsystem that includes remote computers having respective interfaces forreceiving from a server high speed downstream information conveyed overa downstream channel residing in a shared medium and for transmittinglower speed return information over an upstream channel, and whereinsaid asymmetric network communication system includes a networkmanagement unit located at a headend of a broadcast facility foreffecting control of one of switching and routing functions in each ofsaid downstream and upstream channels, a method of dynamically settingtransmit power level of a remote interface comprising:setting a transmitpower level of said remote interface; transmitting from said remoteinterface at least one indication of said transmit power level; andrepeating said steps of setting and transmitting until confirmation of aconfirmed transmit power level is received by said remote interface. 2.The method as in claim 1 further comprising the step of:setting saidtransmit power level of said remote interface to the confirmed transmitpower level.
 3. The method as in claim 2 further comprising the stepof:determining suitability of said confirmed transmit power level. 4.The method as in claim 1 wherein said confirmation comprises a systemspecified number of consecutive responses from said system.
 5. Themethod according to claim 1, wherein said step of setting a transmitpower level comprises the step of:setting said transmit power level to apower level different from previously set transmit power levels.
 6. Themethod according to claim 1, wherein said step of setting a transmitpower level comprises the step of:setting said transmit power level to apower level higher than previously set transmit power level.
 7. In a twoway asymmetric network communication system that includes remotecomputing devices having respective interfaces for receiving from aserver high speed downstream information conveyed over a downstreamchannel on a shared medium and for transmitting lower speed returninformation over an upstream channel, and wherein said asymmetricnetwork communication system includes a network management unit locatedat a headend of a broadcast facility for effecting control of one ofsaid switching and routing devices of each of said downstream andupstream channels, a method of dynamically setting transmit powercomprising:detecting an indication of a transmit power level from saidremote interface; and transmitting to said remote interface confirmationof receipt of said power level indication.
 8. In a two way asymmetricnetwork communication system that includes remote computing deviceshaving respective interfaces for receiving from a server high speeddownstream information over a downstream channel residing in a sharedmedium and for transmitting lower speed return information over anupstream channel, and wherein said asymmetric network communicationsystem includes a network management unit located at a headend of abroadcast facility for effecting control of one of switching and routingdevices of each of said downstream and upstream channels, a method ofdynamically setting transmit power level in said system comprising;atsaid remote computing device:(a) setting a transmit power level of saidremote interface; (b) transmitting from said remote interface to one ofsaid switching and routing devices of said upstream channel at least oneindication of said transmit power level; and (c) repeating said steps ofsetting and transmitting until confirmation of a confirmed transmitpower level is received by said remote interface from said one of saidswitching and routing devices, and at said one of said switching androuting devices of said upstream channel:(d) detecting indication of atransmit power level from said remote interface; and (e) transmitting tosaid remote interface confirmation of receipt of said power levelindication.
 9. The method as in claim 8 further comprising the stepof:setting said transmit power level of said remote interface to theconfirmed transmit power level.
 10. The method as in claim 9 furthercomprising the step of:determining suitability of said confirmedtransmit power level.
 11. The method as can claim 8 wherein saidconfirmation comprises a system specified number of consecutiveresponses from said system.
 12. The method according to claim 8, whereinsaid step of setting a transmit power level comprises the stepof:setting said transmit power level to a power level different frompreviously set transmit power levels.
 13. A method according to claim 8,wherein said step of setting a transmit power level comprises the stepof:setting said transmit power level to a power level higher thanpreviously set transmit power level.
 14. In a two way asymmetric networkcommunication system that includes remote computing devices havingrespective interfaces for receiving from a server high speed downstreaminformation over a downstream channel located on a shared medium and fortransmitting lower speed return information over an upstream channel,and wherein said asymmetric network communication system includes anetwork management unit located at a headend of a broadcast facility foreffecting control of one of switching and routing devices of each ofsaid downstream and upstream channels, a method of dynamicallymaintaining upstream communication between a remote interface and ahybrid routing device, the method comprising:said remote interfacereceiving protocol messages from said hybrid routing device and, basedon said protocol messages, dynamically adjusting a transmit power levelof said remote interface.
 15. The method as an claim 14 wherein saidstep of adjusting comprises the steps of:setting a transmit power levelof said remote interface; transmitting from said remote interface to anupstream portion of said routing device at least one indication of saidtransmit our level; and repeating said steps of setting in transmittinguntil confirmation of a confirmed transmit power level is received bysaid remote interface from said routing device.
 16. The device as inclaim 15 wherein said confirmation comprises a system specified numberof consecutive responses from said system.
 17. The method according toclaim 15, wherein the transmit power level setting step includesproviding means for setting a transmit power level to a power leveldifferent from previously set transmit power levels.
 18. The methodaccording to claim 15, wherein the transmit power level setting stepincludes providing means for setting a transmit power level to a powerlevel higher than previously set transmit power levels.
 19. In a two wayasymmetric network communication system that includes remote computingdevices having respective interfaces for receiving from a server highspeed downstream information over a downstream channel located on ashared medium and for transmitting lower speed return information overan upstream channel, and wherein said asymmetric network communicationsystem includes a network management unit located at a headend of abroadcast facility for effecting control of one of switching and routingdevices of each of said downstream and upstream channels,a device fordynamically setting transmit power level of a remote interfacecomprising;a controller for setting a transmit power level of saidinterface; a transmitter for transmitting from said interface to one ofsaid switching and routing devices of said upstream channel at least oneindication of said transmit power level; and said controller beingrepeatedly operated to alter the power level of said remote interfaceuntil confirmation of a confirmed transmit power level is received bysaid interface from said system.
 20. The device as in claim 19 furthercomprising:means for setting said transmit power level of said interfaceto the confirmed transmit power level.
 21. The device as in claim 20further comprising:means for determining suitability of said confirmedtransmit power level.
 22. In a two way asymmetric network communicationsystem that includes remote computing devices having respectiveinterfaces for receiving from a server high speed downstream informationover a downstream channel located on a shared medium and fortransmitting lower speed return information over an upstream channel,and wherein said asymmetric network communication system includes anetwork management unit located at a headend of a broadcast facility foreffecting control of one of switching and routing devices of each ofsaid downstream and upstream channels, a device for dynamically settinga transmit power level of a remote interface comprising,at one of saidswitching and routing devices of said upstream channel; a detector fordetecting an indication of a transmit power level of a transmission fromsaid remote interface; and a transmitter for transmitting to said remoteinterface confirmation of receipt of said power level indication.
 23. Ina two way asymmetric network communication system that includes remotecomputing devices having respective interfaces for receiving from aserver high speed downstream information over a downstream channellocated on a shared medium and for transmitting lower speed returninformation over an upstream channel, and wherein said asymmetricnetwork communication system includes a network management unit locatedat a headend of a broadcast facility for effecting control of one ofswitching and routing devices of each of said downstream and upstreamchannels, a device for dynamically setting a transmit power level of aremote interface comprising,at said remote interface(a) a controller forsetting a transmit power level of said remote interface; (b) atransmitter for transmitting from said remote interface to said one ofsaid switching and routing devices of said upstream channel at least oneindication of said transmit power level; and (c) said controller beingrepeatedly operated to alter the power level of said remote interfaceand to transmit until confirmation of a confirmed transmit power levelis received by said remote interface from said one of said switching androuting devices, and at said one of said switching and routing devicesof said upstream channel:(d) a detector for detecting an indication of atransmit power level of said remote interface; and (e) a transmitter fortransmitting to said remote interface confirmation of receipt of saidpower level indication.
 24. The device as in claim 23 furthercomprising:means for setting said transmit power level of said remoteinterface to the confirmed transmit power level.
 25. The device as inclaim 24 further comprising:means for determining suitability of saidconfirmed transmit power level.
 26. The device has including 24 whereinsaid confirmation comprises a system specified number of consecutiveresponses from said system.
 27. The device according to claim 23,wherein said means for setting a transmit power level comprises:meansfor setting said transmit power level to a power level different frompreviously set transmit power levels.
 28. The device according to claim23, wherein said means for setting a transmit power levelcomprises:means for setting said transmit power level to a power levelhigher than previously set transmit power level.
 29. In a two wayasymmetric network communication system that includes remote computingdevices having respective interfaces for receiving from a server highspeed downstream information over a downstream channel located on ashared medium and for transmitting lower speed return information overan upstream channel, and wherein said asymmetric network communicationsystem includes a network management unit located at a headend of abroadcast facility for effecting control of one of switching and routingdevices of each of said downstream and upstream channels, a device fordynamically maintaining communication between a remote interface and atleast one of said switching and routing devices, the devicecomprising:programmable means for receiving protocol messages from saidone of said switching and routing devices including means for, based onprotocol messages, dynamically adjusting a transmit power level of saidremote interface.
 30. The device as in claim 29 wherein saidprogrammable means comprises:means for setting a transmit power level ofsaid remote interface; means for transmitting from said remote interfaceto said one of said switching and routing devices at least oneindication of said transmit power level; and means for repeating theoperations of said means for setting and transmitting until confirmationof a confirmed transmit power level is received by said remote interfacefrom said one of said switching and routing devices.